Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
   Satellite Images
   National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
   Winter Weather
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Accomplishments
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
Winter Weather Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 2008Z Nov 19, 2017)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
308 PM EST SUN NOV 19 2017

VALID 00Z MON NOV 20 2017 - 00Z THU NOV 23 2017


DAYS 1-3...

...GREAT LAKES...

AN INITIAL PERIOD OF COLD AIR ADVECTION ACROSS LAKES HURON AND
ERIE/ONTARIO AND LEE AREA LOW LEVEL CONVERGENCE LEADS TO
PERSISTENCE OF THE LAKE EFFECT SNOW SHOWERS THIS EVENING.  THE
HEAVIEST SNOWS ARE EXPECTED TO OCCUR NEAR THE SOUTHEAST CORNER OF
LAKE ONTARIO...WITH THE POTENTIAL FOR SEVERAL INCHES OF
ACCUMULATION.  THE UNCERTAINTY LIES WITH BAND EVOLUTION AND
CHANGING WIND PROFILES THAT LEADS TO THE BAND(S) CHANGING
LOCATION. THE 12Z MODEL RUNS SHOW WINDS BACKING WITH TIME...SO THE
LOCATION OF BANDS SHOULD SHIFT NORTH OVERNIGHT AND MONDAY MORNING
OFF OF BOTH LAKES ERIE AND ONTARIO.  THE BANDS OFF THE SOUTHEAST
CORNER OF LK ONTARIO TONIGHT SHOULD SHIFT TO EAST OF THE LAKE MON.
 THE CHANGING LOCATION LEADS TO A LOW PROBABILITY OF A LONGER
DURATION HEAVY SNOW SNOW EVENT IN ANY ONE LOCATION.

...PACIFIC NORTHWEST/NORTHERN ROCKIES...

A VIGOROUS FRONT AND ASSOCIATED UPPER DIVERGENCE MAXIMA IN THE
COUPLED REGION OF THE JET WILL BRING HEAVY MOUNTAIN SNOWS TO THE
NORTHERN WA CASCADES SUN EVENING. WPC DAY 1 PROBABILITIES CONTINUE
TO INDICATE A SIGNIFICANT THREAT FOR ACCUMULATIONS OF A FOOT OR
MORE OVER THE HIGHER REACHES OF THE NORTHERN WASHINGTON CASCADES. 

THE JET EXTENDS FURTHER INLAND INTO THE NORTHERN ROCKIES...WITH A
SECOND AREA OF HEAVY SNOW IN THE RANGES OF CENTRAL TO NORTHERN ID
AND NORTHWEST MT.  A BREAK DEVELOPS IN THE CASCADES AS DRIER AIR
ALOFT ADVECTS INTO THE REGION MONDAY. 

THIS SYSTEM IS EXPECTED TO WEAKEN AND DEPART FOR THE PLAINS
MONDAY. AN UPPER JET MAXIMA EXTENDS EAST FROM OR AND ID INTO
NORTHWEST WY.  ON DAY 2 THE PRIMARY FOCUS IS WHERE UPPER
DIVERGENCE MAXIM IN THE UPPER JET CROSS OVER THE RANGES OF
NORTHWEST WY...WHERE LIGHT SNOW ARE EXPECTED MON NIGHT-EARLY TUE.
SNOW LEVELS WILL BE ON THE INCREASE AS A STRONG RIDGE CONTINUES TO
BUILD ACROSS THE WESTERN U.S. 

ON DAY 3 (TUE NIGHT-WED)...WPC PROBABILITIES SHOW LITTLE POTENTIAL
FOR HEAVY SNOW ACROSS THE U.S. A FEW ENSEMBLE MEMBERS SHOW A
CONTINUATION OF LIGHT SNOW SHOWERS IN THE RANGES OF NORTHWEST WY.
MOST MODELS/ENSEMBLE MEANS DO NOT SHOW ANYTHING BEYOND A SPOTTY
INCH OR TWO.

FOR DAYS 1-3...THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN
10 PERCENT.

PETERSEN